Four of the squad left to abduct him, Shumate said. When they returned with a prisoner, Shumate said he was "told to fire" by the squad leader.

He learned later that it was Awad, whom prosecutors have described as a disabled father of 11.

The eight men are also accused of planting a gun and a shovel next to the body to make him look like he was planting bombs. The shooting was one in a series of incidents in which the conduct of American troops in Iraq came under scrutiny.

Other US marines based at Camp Pendleton are under investigation over a separate incident in November 2005 in which 24 civilians were killed in the Iraqi town of Haditha.